Contaminated construction sites are those which possess risk to human health and environment. With the increase in demand for infrastructure development around the world and shortage of land available for the same, contaminated sites may be used for new construction projects.
The Contaminated construction site can be the result of:
- Any industry in the past on current site
- Wastes being dumped at site
- Contamination through chemicals used for agricultural purposes
- Contamination in site filling materials
- Soil contamination through demolition of existing structure.
The presence of chemical contamination of soil or ground about to subside creates risk of health hazards for construction workmen.
Following are the objectives for contaminated construction site investigation:
1. To identify the types of hazards, their extent and importance for assessment of potential risks to human and environment.
2. To identify suitable remedial measures for the existing contamination hazards.
The hazards that may occur at contaminated sites are:
1. Settlement problems of ground such as ground subsidence due to decomposition, weathering and natural compaction soil, leaching and sudden collapse.
2. Obstructions from existing remains of old foundation, buried walls, pile foundations etc.
3. Radioactive substances, biological contaminations, toxic powders, asbestos, fibres, liquids, explosives etc. which can attack construction workers.
4. Fire, smoke, gases, volcanic areas, microbial reaction of organic matter, explosions from combustible materials etc. posses greater risks for construction personnel.
5. Contamination affecting the construction materials with chemical reactions, contaminated ground and ground water can affect the health of humans.
6. Polluted streams of water, aquifers, wind action on contaminated dusts etc. which may affect the health.
The site investigation for contaminated soil is not sufficient just by observation of ground surface conditions and the investigation needs to be carried out for more details on the ground conditions below the site. The extent and intensity of this investigation depends on the type and project and its magnitude, conditions of construction site and its variations.
The code of practices for contaminated soil investigation for construction should be followed as per the local applicable standards. The investigation should be properly planned and executed sufficiently to get all the data pertaining to ground conditions to minimize the risk of health hazards to workmen and damage to the environment.
Too little investigation of contaminated sites may not reveal potential hazards of construction site and extra expenditure will be required for safety, while in-depth site investigation more than required may prove to be uneconomical for construction project.